Telegraph repeater



y 1 936. E. 'r. BURTON 2,039,629

TELEGRAPH REPEATER Filed Oct. 23, 1930 3 Sheets-Sheet l CHARGE. "E I A AA V IMPULSECOIIL OUTPUT V CONDENSER VOLTA 6E INVENTOR E. T. BUR TONATTORNEY May 5, 1936. E. "r. BURTON 2,039,629

TELEGRAPH REPEATER,

Filed Oct. 25, 1933 3 Sheets-Sheet 2 FIG. 8 A A J v V A A A 42 V IMPULSECOIL OUTPUT \r FIG Q CONDENSER VOLTAGES FIG. 10

lNVE/VTOR 1:. 7T BURTON By j A TTORNEV y 1936- T. BURTON 2,039,629

TELEGRAPH REPEATER Filed Oct. 23, 1930 3 Sheets-Sheet 3 IIII 3 FIG, 12I67 -g g fg-las AAA IV FIG. 13

- INVENTOR E. 7'. BURTON.

"5 jibe/M Patented -May 5, 1936 UNITED STATES" 2,039,629 TELEGRAPHanrrn'rna Everett T. Burton, Mlllburn, N. J... asslgnor to BellTelephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New York Application October 23, 1930,Serial No. 490,585 20 Claims. (01. 178-70) s This invention relates totelegraph systems and 'more particularly to repeaters for regeneratingimpulses for further transmission in telegraph and similar impulsetransmission systems such as picture transmission and televisionsystems.

An object of this invention is to reduce distortion in telegraphsignals.

Another object is to reshape attenuated anddistorted signals ofirregular amplitude into corresponding signals having a substantiallyflattopped wave of uniform amplitude.

Heretofore, two general types of repeaters have been employed, i. e.,electromagnetic relays and thermionic or vacuum tube amplifiers.Electro-' 16 magnetic relays have been commonly used for reproducingsquare-topped waves such as are used in telegr'aphy, while vacuum tubeamplifiers have been preferred for reproducing without distortion, wavesof varying intensity.

20 However, a repeating circuit for telegraph signals has been proposedwhich utilizes vacuum tubes in place of electromagnetic relays and whichmay produce in its output circuit a substantially square-topped wave.United States patent to Krause 1,537,682, May 12, 1925 discloses such asystem in which fiat-topped waves are produced in the output circuit ofa vacuum tube whenever the input voltage exceeds a certain value. 'Negative grid voltages in excess of that value produce no further change inthe output voltage because the space current is completely blocked. Onthe other hand, positive grid voltages in excess of that value produceno further change in the output current'because of filament saturation.A disadvantage of that arrangement is that disturbing currents of smallvalue are amplified greater proportionally. than the signal impulses. I

It is, therefore, a further object of this inven- 40 tion to eliminate,by means of a thermionic repeater, disturbing currents of less than apredetermined amplitude.

' A sum further object of thls'invention is to provide a thermionicrepeater in which the polarity of the repeated impulses is independentoi-the characteristics of the thermionic or vacuum tubes, and dependentonly upon the establishment or definite values of voltage of thereceived signals.

In accordance with the above stated objects,sig-

naling impulses are received in the form of a wave which a greatlyoverloaded magnetic circuit is utilized. The impulses or kicks may beselected to occur within any desired range of intensity ofv current uponthe rise and fall of current intensity.. This method is described morefully in U. S. 5 Patent 1,936,153, granted to E. T. Burton on November21, 1933. As a next step, these sharp discrete impulses are lengthenedby means of a vacuum tube arrangement which reproduces wavescorresponding to the incoming line signals 10 in polarity, but having asubstantially flat top. The impulse coils serve as mutual impedances inthe input circuits of said vacuum tube arrange ment. 7 I

Another object of this invention is to provide 5 a repeater of the typedescribed which is capable of operating at a high speed. In the presentinvention, mechanical relays, which are subject to chattering at highspeeds, are rendered unnecessary. 20

'The arrangement for lengthening the impulses may be embodied in any oneof several forms. According to one embodiment, the output circuit of theimpulse coil is connected to the grid circuits of two thermionicdevices, such as vacuum tubes, 25 wherein are provided condensers forstoring the signals. The thermionic devices may be described asrectifying or unidirectlonally conducting de- 'vices., Each condenserbecomes charged to one polarity on the receipt of an impulse from the 30impulse coil and maintains a charge upon the grid until a change ofsignal polarity occurs, at which time the condenser is discharged. Afeature of this'arrangement resides in means for reproducingthree-element signals, that is, sig-, 35 nals consisting of positive,negative and zero impulses. a 1

According to another embodiment of this invention, two three-electrodedevices, such as vacuum tubes, are arranged so that the grid circuit 40of each tube is coupled to the plate circuit of the other, whereby anincrease of current in the plate circuit of one tube is eflective-todecrease the plate current in the other tube until the latter platecurrent is blocked. This system is stable 45 in two positions, in whichthere is a steady plate current inone tube or the other, depending onthe polarity of the last received impulse. The threeelectrode devicesmay also be described as rectitying or unidirectionally conductingdevices. 50

Other objects and features of this invention will appear more clearlyfrom the following de-&

scription' taken in connection with the accom- 7 mm: drawings andappended claims.

schematically a circuit including a storing condenser and embodying thepresent invention;

Fig. 2 is a simplified diagram showing the connections to the storingcondenser of Fig. 1;

V Fig. 3 illustrates a signaling wave received by the repeater circuitof -Fig. 1;

Fig. 4 shows the current in the secondary trans former windings of thecircuit of Fig. 1;

Fig. 5 shows the condenser voltage for corresponding points on theincoming signal curve shown in Fig. 3;

Fig. 6 is a modification of the circuit of 1 1g. 1, which constitutes athree-element relay;

Figs. 7 to 10 inclusive, illustrate a repeated signal at differentstages in its retransmission by the circuit of Fig. 6;

Fig. 7 shows an incoming signal;

Fig. 8 shows the outputvoit'ages of two windings of the transformer;

Fig. 9 shows the voltages of the two respective condensers;

Fig. 10 shows the voltage of the two condensers in series;

Fig. 11 is a schematic diagram of another modification of the presentinvention and shows a regenerative locking repeater; and

Figs. 12 and 13 are still, further modifications which embody thefeatures of the circuit shown in Fig. 11.

Referring to Fig. 1, a repeater is connected to retransmit from theincoming line III, to the outgoing line "I I. Connected to the incomingline" II is the primary winding of a transformer 12. The transformer isof a type having ahigh permeability core which becomes saturated at avery low magnetizing force. A transformer of this type is commonlyreferred to as an impulse coil, and is described in U. 8. Patent1,936,l53, supra. The impulse-coil I! has two secondary windings l4 and2l. The winding I4 is connected serially with a condenser II andresistance It, while. the winding 24 is similarly connected in a seriescircuit with a condenser 25 and a resistance 28. Two space dischargedevices such as vacuum tubes l1 and 21 each have their grid circuitsconnectedin parallel with the condensers I5 and 25, respectively. Thegrid circuits plate circuits of these vacuum tubes are arranged so thatthe condenser 30 is in series with each plate circuit. A B battery II isinterposed in the plate circuit of vacuum tube ii. The output voltage ofthe above described vacuum tube arrangement is supplied from the plateandfilament respectively of vacuum tube l1, and is impressed on the gridcircuit of amplifier tube 33 whose plate circuit is connected to theoutgoing line ii; The C batteries i8 and 29 are desirably of sufllcientvoltage to block the plate current to zero when a plate voltage equal tothat of battery 3| is applied to either tube.

The function of the condenser 30 can best be understood by reference toFig. 2. When the grid of vacuum tube i1 is positive and the grid of 21negative, the current flows through the plate circuit of vacuum tube I Ito charge'the condenser 30 to the voltage of the B battery ii. The

I capacity of the condenser 30 is small and, there- .fore, the condenserbecomes charged to the full battery voltage almost immediately. when thegrid of vacuum tube 21 becomes positive and that of i1 becomes negative,a discharge path for the again becomes positive. The grid circuit ofvacuum tube II is connected in series with condenser and the B batteryIi. It follows that the grid voltage of vacuum tube 33 is equal to thevoltage of battery 3i minus the sum of the condenser voltage and any "0battery voltage that may be employed. (when the condenser is fullycharged, the condenser voltage neutralizes the voltage of the 3" batteryII and the grid voltage of the amplifier tube 33 becomes equivalent tothe voltage of the "0 battery alone. when the condenser is dischargedthe grid voltage is equal to that'of battery 3i minus the 0" batteryvoltage.

The manner in which a received signal is transferred from the incomingline II to the outgoing line II will now be explained. In Fig. 3 isillus-v trated the waveform of a somewhat distorted signal made up ofone positive, one negative, two positive and one negative impulses. Thetwo lines A and B in Fig. 3 represent the current values at which thetransformer becomes saturated. It is apparent that the only time anycurrent is induced in the secondary winding of the transformer orimpulse coil l2 occurs when the current strength of the received signallies between the values Band A.- It will be seen that only a short timeelapses during the change in current strength from B to A or viceversa." The electromotive force induced in the secondary windings of theimpulse coil is shown diagrammatically in Fig. 4. The secondary windingsof the impulse coil induce discrete impulses of short duration which areof one polarity when the incoming signal passes from the value B.to A,and of the positive when the incoming signaling current changes. fromminus to plus (B to A), the con-- denser '30 begins charging andtherefore becomes fully charged whenever the incoming current ispositive. and above the saturation point. The condenser is dischargedduring the time that the incoming impulse is correspondingly negative.-

The outgoing mum the line H has a shape" corresponding to the signalshown in Fig. 5. It will be observed that the signal of-Fig. 5.1asquaretopped as contrasted with. irregular signal shown in Fig.3. Thesquare-topped eflect is due to the fact that the voltage of thecondenser 30 has but two alternative values and quickly changes from onevalue to the other whenever the received signal current passes betweenthe values A and B.

The circuit of Fig. 1 may be modified as shown in Fig. 6 to make athree-element relay. The impulse coils 42 and "of Fig. 6 each replacethe impulse coil l2 of 1 and are oppositely biased. The impulse coil 42has a pair of secondary windings 44 and 54- corresponding in function tothe pulse coil 52 has a similar pair of secondary windsecondary windingsl4 and 24 of Fig. 1. The imings 64 and 14. The secondary windings are 7connected to the grid circuits of vacuum tubes ll, 51, t1 and",respectively, which are connected to the windings in a similar manner tothe corresponding elements in the circuit of Fig. 1. A condenser Isimilar to the condenser ll of Fig. 1 is connected in series with theplate cir- 2,039,629 cult of .either tube" or 51. Similarly, condenserII is connected in series with .the plate circuit of either tube 61 or11. The condensers 60 and I are connected in series with each other andwith a battery 12 and the grid circuit of an amplifler tube 13. Thevacuum tubes or similar triodes 41, 51., 61 and 11 are supplied withplate voltage by the common B battery "which connects the plates oftubes 51 and 61 tocondensers 00 and 10.

The operation of the circuit shown in Fig. 6 can best be understood byreference to the curves shown in Figs. 7 to inclusive. The incomingsignal wave, as before, isshown in Fig. '7 as consisting of a positive,negative, two positive and one negative impulses. The impulse coil 42 isbiased so that it is saturated for any current value below the line D orabove the line C. The impulse coil 52 is biased in the oppositedirection and this impulse coil is saturated at current values below theline E or above the line F.

As shown in Fig. 8 (see curve 42") an electromotive forceof highamplitude and short duration is induced in the secondary windings ofimpulse coil 42 when the received current strength passes between thevalues C and D; and an electromotive force is induced in the secondarywindings of impulse coil 52 (see curve 52') when the incoming signalpasses between the values E and F. The polarity of the inducedelectromotive force is, of course, determined by whether the signalingcurrent is increasing or decreasing as it passes between the values Cand D, and E and F,

respectively.

Fig. 9 shows the voltages of the condensers 60 and I0, respectively. Thecurve 60' corresponding to the condenser 60 resembles somewhat the curveshown in Fig. 5. The condenser 60 is 'charged in the same manner as thecondeser 30 of Fig. 1, but on account of the bias of the impulse coil 42the zero voltages are of longer duration than the positive voltages. Thecurve 210' corresponding to condenser i0 shows two voltage values, oneof which is gem and the other negative. The condenser I0 is connected tothe battery II in a different manner from the condenser 00 and, inresponse to the incoming signal of Fig. 3, the negative voltageconditions in condenser 10 are of shorter duration than the zerovoltages.

The total voltage of condensers 00 and I0 connected in series isas shownin Fig. 10. Comparing the output voltage shown in Fig. 10 with'theinput'currentor voltage of Fig. '7, it will be seen that the device ofFig. 6, like the circuit of Fig. 1 produces flat-topped. signals.Furthermore, it will be noted that the incoming signal in passingbetween the current value E and the value C produces a zero voltage inthe output circuit. The advantage of converting the current strengthsbetween the values E and C into zero voltage is that signals betweenthese values are mitted signal. The device of Fig. 6 avoids thepossibility of transmitting-stray pr interfering disturbances, bysuppressing all signals not sufficiently strong to reach the valueC or EA type of two-elementthermionic tube relay employing the regenerativelocking principle is illustrated inFigi 11. A pair of three-electrodedevices such as vacuum tubes are provided and the polarity .of therepeated i nal is. determined by the tube which is supplying currentthrough its plate circuit. Y

I Referring more particularly to Fig. 11, the incoming line H0 isconnected to the primary winding of a high permeability transformer orimpulse coil H2 adapted to become saturated at a comparatively lowcurrent value. Connected to the, secondary transformer winding in amanner to be describedpresently, are a pair of vacuum tubes ill and I21.A pair of resistances I and I30 are connected in series with each other,the resistances forming a part of the plate circuits of the vacuum tubesII? and I2! respectively.

The grid circuits of the vacuum tubes Ill and I211 respectively areconnected so that when space current flows in the plate circuit ofeither tube, the grid'of the other tube is blocked toe. negativepolarity by the potential drop through the resistance I20 ,or 030 in theplate circuit of the first tube. The grid circuit of vacuum tube II'I isconnected across resistance l30, while the grid which is connected tothe output line i I l, is supplied with the potential drop acrossresistance iii], although, as an alternative arrangement, this gridcircuit may be connected across the resistance I30.

The circuit shown in Fig. 11 has only two points oi stability. In onestable condition, current flows through the resistance I20 "andnot'through resistance I30, while in the other stable condition currentflows through resistance I30 and not through I20. The repeater of Fig.11 remains in one or the other stable condition until the grid voltagesare reversed by an impulse from the transformer M2. By employing atransformer delivering a very short high amplitude impulse. the time ofsignal crossover-or reversal of polarity-in the output circuit ofthe-repeater may be reduced almost to zero. When such a transformer isemployed the crossover point on the incoming wave, at which the repeaterchanges from one stable condition to another, is independent of thecharacteristics of the vacuum tubes and dependent upon the permeabilityand saturation points of the transformer.

A three-element relay operating on the same principle as the two-elementrelay of Fig. 11 is shown in Fig. 12. Essentially the circuit of Fig. 12comprises .two circuits similar to that of Fig. [111 with their outputsconnected in series. A pair of biased impulse coils I42 and I52 are usedto operate the relay, each impulse coil controlling the operation of therepeater for one polarity of the incoming signal. Assuming an incomingwave of the shape shown in Fig. 7, the impulse voltages of the secondarywindings I44 and I64 of the impulse coils, I42 and I52 respectively willbe as indicated by the curves 42' and 52 respectively of Fig. 8 andtheir directions are indicated by arrows shownadjacent to theirrespective windings in Fig. 12. The'vacuum'tubes I41 and I51 respond tothe impulses received from impulse coil I42 and cooperate in' a mutuallylocking arrangement similar to that of Fig. ll, to-control the voltageacross resistance I40. Similarly vacuum tubes I01. and I'll control thevoltage across resistance I50. The resistances I and I are connected inseries, and the output terminals I and I10 areselectedto. obtain thecombined voltasedropacrossbothresistances. Itwillbe noted that vacuumtubes I" and III are connected to the secondary winding I in oppositerelation to the connection of vacuum tubes Ill and I" to the secondarywinding III. In other words vacuum tubes In and III are connected to thelower end of winding Ill whereas the vacuum tubes I" and I" areconnected to the upper end of winding III. Therefore, a polarity of animpulse shown in curve I! will have, when impressedon the grid of vacuumtube I41, the op- .incurvell'oil lg.8,isoccurringinsecondary winding Idue to the incoming signal wave shown in Fig. 7, passing through therange 01 intensities between lines 0 and D. This positive impulse causesthe grid oi vacuum tube Ill to become negative, thereby blocking thespace current in tube I" and causing space current to flow in vacuumtube III. The space current in tube I51 produces a voltage drop acrossresistance Ill. This voltage counteracts an equal drop across resistanceIII produced by the previous impulse in secondary winding III. Theeiiect therefore 01' the voltage drop across resistance III is thatterminal I'll goes from negative to zero potential as indicated by theilrst zero section in the curve shown in Fig. 10. s When the incomingsignal wave rises to the positive side and passes through the valuesbetween the lines E and FiFig. 7), a positive impulse occurs insecondary winding I" to impress a positive potential on the grid of tubeI"; This results in changing the stable co I dition of tubes I11 and it!established by the p vious impulse in winding III, so that space currentnow flows in tube I11 causing a voltage drop across resistance III, andthe space current in tube III-is blocketL- At this time the stablecondition 0! tubes I" and I I1 is such that avoltage drop'ex-- istsacross resistance I due to the first impulse shown in curve (of Hg. 8,and no voltage drop exisis across resistance III. The eilect oisimultaneous voltage drops across resistances III and I and of novoltage drop across resistance III is to impress a positive potential onterminal "I and the output voltage'ot the circuit goes fromzerotopositiveasindicatedby theflrstpodtive section of the curve shownin Fig. 10.

When the incoming 818ml wave decreases in intensity and returns throughthe values between the lines 1' and E (Fig. '1), a negative impulseoccurs in secondary winding I impressing a negative potential on thegrid of tube Ill. The stable condition of tubes I11 and III due to theflrstimpulse shownincurve I2'ot1'lg.8,isagainchangedsothatthespacecurrentin the tube I" is now blocked and spacecurrent flows intube lIlproducingavoltagedropacrossresistance III. Atthis time the stable condition .oitubesIl'landIIIisthesameasstatedlntheprevious paragraph, that is, a voltage drop exists across resistance I.

V The eil'ect oi simultaneous voltage drops across resistances III andIII isto-restosethepotenflalontermlnal I'Iltoaa'o voltage of thecircuitgoes mm creases in intensity, becomes negative and through the valuesbetween lines 0 and D (Fig. 'I), a negative in winding I to impress apositive potential onthe grid of tube I". The positive potential on thegrid changes the stable condition of Iaibes Ill and III 7sothatspacecurrentnowflowsintube Ill and the space current in tube IIIis blocked. The space current in tube ll'l produces a voltage dropacross resistance III and no voltage drop now exists across resistanceI. At this time the stable condltion'o! tubes I" and III is such that'avoltagedropexistsacromreslstance IIlandno whentheincomingsignalwave(FlgL'Dispassing through intensifies between lines D and If,

the potential diflerence between terminals Ill.

and III is zero. when the intensity is above line 1",thep0t0ntlalattermlnal I'|l,withrespectto terminal m, is positive and when belowlineD the potential at terminal III is negative.

The output voltages across terminals III and III are of a shapesimilarto that oi! the curve shown in Fig. 10 that is, oi! positive, negativeand zero polarity and constitute a\ three-element signal wave. Thereproduced signals are flattopped, and those impulses which have a leuers'tiengththanlorcarenotretransmitted.

InFig.l3isshownaslightmodiilcationoithe" -The lllandlllareinthesridircifl of both tubea'llland II'I.

Theiollowingieaturuoitherelaysoil'lgs. 11,12and13areinsfimnentalineilectimreliabiliiw oioperation: J

Intheilrstplace,the'inputvolta gessupplled to the grid circuits areobtained from impulse coilsratherthandirectlytromtheincaningline.

Bymeansortheiuipiulaecoilsthleviilueofincomingcurrentstreiutpbelowwhichasianaliscanbewlthaccuracy .bysimplyvarylnlflleflaalngcurrentintheimpulsecoila.Whentbeeurruitvaliiecrossesa predeterminedlinetheimpulseeoilsproducea.impiflaeorwwhieh'instantlychanses tbcvacmmitubeflate circuits Iroma-stable conditionotonepolarltytooneotanotherpo- 'larity.Thusthetlmetakeniortheoutgoingsig-.naltochange'nomonepohritytoanotherisverysmallandisturthermi'netotanyvarlationsinthecharaete'rlsticaclthevacuumtubes.lithegrldcircuitsottbsvacuumtuhswereconnecteddirectly'totheincnminglinewithouttheinterpositionotimpuhscolhtheresponsetoa .cha aeinpola troriteosthottheneeivedsisnaiwouldbeneitber asnfldnorasresularasinummmmmmmnmimpulsecdls. v'lhe-responseoi'thegridcircuits with when, on the otherhand, impulse coilsare employed the relay may operate indefinitelywithout requiring adjustment or the vacuum tubes.

The plate impedance of the vacuum tubes of Figs. 11, Hand 13 iscomparatively low when the grid is locked to the positive polarity forthe reason that no grid biasing batteries are used. Thus the platecircuit resistance and the B battery voltage become the chief factors indetermining the output voltage. The output being taken from two o! thefour plate resistances only, at most two B battery units areinstrumental in determining the output voltage. In the circuit of Fig.13, the question of battery matching is eliminated since a single Bbattery unit furnishes both output polarities. When a grid is locked tothe negative polarity the voltage is 'suihcient to reduce thecorresponding space current to zero.

ing and an outgoing line, instrumentalities connected to the incomingline for producing a succession of short, sharp, discrete impulses inresponse to the establishment of definite magnitudes of voltage 01 eachincoming signal impulse,

space discharge devices responsive to said discrete impulses, a platecircuit for eachQ said devices, a single space discharge deviceinterconnecting said plate circuits and the outgoing line, and impedancemeans in one of said plate circuits for controlling the output voltagein the other of said plate circuits. s

2. In a repeater for signal impulses, an incoming circuit, two spacedischarge devices each having a cathode and a control element connectedto its input circuit, anode-cathode output circuits, an outgoing line towhich impulses from an incoming line are to be repeated, polarizingsources for equally and symmetrically polarizing each.

control electrode with respect to its associated cathode, said controlelectrodes being coupled by equal mutual impedances, but oppositely, tosaid incoming circuit, and a potential storing device connected incommon to said anode-cathode circuits and having impedance equally andoppositely coupled to said anode-cathode circuits, said device beingalso coupled to said outgoing line'.

13. In a communication circuit, a signal repeat- 'er comprisinginstrumentalities for producing-in response to each received signalimpulse, a sucsession of short, sharp, discrete impulses of oppositepolarities, mutually locking devices adapted to change from one stablecondition to another in response to each of said discrete impulses, anda space discharge deviceadapted to remain stable in one of a pluralityof conditions and solely responsive to said -discrete'impulses11orchanging from one of its conditions to another.

4. In a signaling system, a repeater'comprisinga plurality of spacedischarge devices, a plate circuit to; each of said devices, a condenserconnected in series in each of said plate circuits, an instrumentalityresponsive to a received impulse of one polarity and arranged tocooperate with one'of said devices in charging said condenser, anotherinstrumentality responsive to a received impulse oi! the other polarityand arranged to cooperate with another of said devices in dischargingsaid condenser, and a space discharge amplifying device for transmittingsignals or a polarity determined by the voltage of said condenser.

5. In a, signaling system, a repeater comprising a condenser, meansresponsive to a received impulse of one polarity for charging thecondenser, means responsive to an impulse of another polarity fordischarging the condenser, said discharging means comprising a spacedischarge device having a control electrode responsive to receivedsignals, and means for transmitting signals of a polarity determined bythe polarity of the voltage of the condenser.

6. In -a signaling system, a repeater comprising a condenser, meansresponsive to a received impulse of one polarity for charging the con;denser, means responsive to a received impulse of another polarity fordischarging the condenser, and means, for transmitting signalscomprising a thermionic amplifier having a control electrode connectedto the condenser, whereby to prevent rapid discharge of the condenserthrough the transmittingmeans.

7. In the operation of asignaling system, a method of reshaping incomingdistorted signal impulses which comprises converting each of thedistorted signal impulses into a plurality of impulses oishort durationand of opposite polarity, and subjecting each of said impulses 01 shortduration to a relatively high, impedance to produce a voltage sustaineduntil the next succeeding-short impulse is produced, to i'orm atwoelement square topped wave.

- 8.'l'n the operation of a signaling system, a method oi. reshapingincoming\dist0rted "signal impulses of positive and negative polaritywhich comprises converting each or the distorted impulses into aplurality of impulses ofshort duration and of positive and negativepolarities, subiecting alternate pairs of said short impulses ofopposite polaritiesto a relatively high impedance to produce a voltagesustained until thenext succeeding short impulse alone and of theopposite polarity is produced, subjecting other alternate pairs of, saidshort impulses of opposite polaritiesat different intervals'from thoseof the first mentioned alternate pairs whereby ,the voltage produced byone of the impulses oi! said other alternate pairs is sustained untilthe next succeeding short impulse of said other alter-- nate pairs isproduced, and combining the sustained voltages in their time relation toform a three-element square topped wave.

9. In a signaling system a circuit arrangement for reshaping distortedsignals comprising electromagnetic devices forconverting each of thedistorted signal impulses into a plurality of voltagedmpulses of shortduration and of positive and negative polarities, unidirectionallyconducting means for selecting certain of said voltage impulses toproduce sustained voltages of a polarity dependent upon the polaritiesof the voltage impulses of short duration, impedancemeans for furthersustaining the voltages of the output of said unidirectionallyconducting means, and means for repeating the further sustained voltagesas undistorted signal impulses corresponding to those received by' saidelectromagnetic Ierences across the two impedance elements beingdevices, the repeated signal impulses having a polarity determinedsolely by the polarity of the corresponding sustained voltages.

10. In a communication system, a signal repeater comprising two spacedischarge devices, a condenser, a charging circuit for said condenserincluding one space discharge device and a discharge circuit i'or thecondenser includingthe other space discharge device, each spacedischarge device having control means for succes-v sively blocking andpermitting space current in 7 response to received i nals.

11. In a communication system, a signal repeater comprising two triodes,each having an anode, a cathode and a control electrode, a condenser, acharging circuit for the condenser including the anode and cathode ofone triode, a discharge circuit for the condenser the anode and cathodeof the other triode, inductive circuits including the control electrodesfor controlling the current through the triodes in re-' sponse toreceived signals, and a spacedischarge device for transmitting repeatedsignals having a polarity determined by the charge oi! the condenser.

12. In a signal on system, a repeater for suppressing signals having'less than a predetermined magnitude, comprising a first impedanceelement, mutually locking devices responsive to incoming signals formaintaining in approximately constant potential difierence across saidimpedance element only while the incoming signal strength exceeds apredetermined positive value, a second impedance ele other mutuallylocking devices for maintaining an approximately constant. potentialdiiierence across said second impedance element only while the incomingsignal strength exceeds in negative polarity a predetermined value, thepotential difopposite in polarity, and a transmitting device connected;sin series with both impedan' ce elemen 13.1nasignalrisystemarranged toreceive two element slgnal waves,a repeater 1'or supp signals havingless than a predetermined magnitude, comprising a condenser, meansresponsive to incoming signalsior suc- 50 cessively charging and thecondenser fierandsopoiedtlnteurrentinoneampllfier "is efi'ective toblock current in the-other ampli- -fier, inductive device forcontrolling the input in mm tbeestabliahmmtol definite inasnitudes orvoltage of the incoming signals.

15. Inasignalingsystem,'arepeatercomprising J5apairotthermionicampiiflermmhblvi lm ment in series with the firstimpedance element,

system,asignalrecircuits oi the amplifiers, said devices being,adaptedtoproduceshort,sharp,-disereteimpulses output circuit comprisingan impedance element and an input circuit supplied with voltage from theoutput impedance element of the other thermionic'amplifier, the inputcircuits being so poled that output current from one amplifier blocksoutput current in the other amplifier, inductive devices responsive tosignals received from a line for controlling the input circuits of thethermionic amplifiers, and a transmitter for repeating the incomingimpulses, said transmitter being connected to the two output impedanceelements in series.

16. In a signaltransmission system arranged to receive two elementsignal waves, a repeater comprising oppositely biased inductive devicesarranged to eiIect the suppression of signal intensities of a pmitivepolarity and of anegative polarity except those within a predeterminedrange and .to convert the rising and falling portions of a signalwavewithin said range into short, sharp, discrete impulses of oppositepol'arity, a plurality of mutually locking space discharge devicesresponsive to said short impulses, a pair oi. impedance elementsrespectively connected in the output circuit oi each 01' said lockingdevices whereby each pair of short impulses oi opposite polaritiesproduces potential differences across said impedance elementsalternately, a

transmitting device connected in series with the pairs of impedanceelements whereby each 0! the short impulses-is efiective to cause saidtransmitting device to transmit or repeat an impulse of positive,negative or zero voltage to form a threeelement signal wave.

17. In a repeater for signal an incoming and an outgoing circuit, devicufor receiving from said incoming circuit signal wave impulses of slowlyvarying intensities and for producing a' succession of short, sharp,discrete impulses in response to the establishment oi definitemagnitudes of voltage in each incoming signal wave im'-. pulse, a pairof thermionic valves. each having a cathode, anode and an impedancecontrol element, circuit means'conecting the anode oi one valve and theimpedance control element of the other valve to said devices, andadditional circuit means interconnectingthe input and output circuits ofsaid valves and said outgoing repeater circuit whereby said valvesassume two stable conditions alternately in response to said discreteimpulses.

18. In a repeater for signal impulses, according to claim 17, saidadditional circuit means-comprising a connecting lead between theimpedance control element oi said other valve to the platefcircuitoi'saidone valve,completing'circuitmeans whereby an electricalimpulse of one polarity applied to the impedance control elemmt ofeither valvecauses a change of plate circuit current in that valvewherebythe piatecurrentotonevaiveisreducedandzthatottheothervalveincreased until one of said stableconditions is attained and maintained until an applied impulse oi!opposite 'p larityreversesthe processactuatingsaidvalm to assume theother and opposite stable condition. I v

19. In a system for communication of intelligence arepeater having andoutgoing circuits, means in said incoming circuit and responsive toincoming distorted signal waves forproducingasuccessionofshortdiscreteimpulsee inresponsetochangcsoi'magnitudeotvoltage of said waves througha fixedrange ofmagnitudes, the polarity-of said discrete impulses being determined bythe direction of change 01 laidvoltage through said fixed range,thermionic discharge means alternately and oppositely responsive toimpulses of positive and negative polarity,

an impedance element connected in common to' said thermionic dischargemeans and arranged to cooperate therewith in producing for each pair ofshort discrete impulses of positive or negative polarity by themselves,a sustained voltage wave of square topped shape and equal in duration tointervals between the impulses of the corresponding pairs, and anotherthermionic discharge device connected to said outgoing circuit ioramplifying said sustained voltages for retransmission.

20.,In a repeater for signal impulses, an incoming circuit connected toa source of signal impulses, two space discharge devices each having acathode and a control element connected to its input circuit, and ananode-cathode output circuit, an outgoing line to which the impulsesfrom an incoming l'ne are tovbe repeated, a path com mon to bothanode-cathode output circuits and in shunt to said outgoing line, andelectrostatic I EVERETT T. BURTON.

' means arranged in said common path to cooperate v

